Hydrogen diffusivity in dislocation, grain boundary, and lattice of α-Fe based on electrochemical hydrogen permeation experiments and Maxwell-Garnett calculations

We elucidate the hydrogen diffusivity in α-Fe with different dislocation densities, grain sizes, and textures obtained by different annealing after cold rolling based on electrochemical hydrogen permeation experiments and Maxwell-Garnett calculations. A unique inflection point was found to calculate the hydrogen diffusion coefficient, which reflects the threshold from accelerating to decelerating hydrogen diffusion. Texture has significant influences on hydrogen diffusion, and hydrogen atoms in α-Fe lattice diffuse along <111> direction much slower than in other directions. Based on Maxwell-Garnett calculations, the hydrogen diffusion coefficients of dislocations, grain boundaries, and α-Fe isotropic lattice are 4.4×10 ⁻⁴, 2.3×10 ⁻⁴, and 2.5×10 ⁻¹⁰ m ²/s, respectively.